Pen-type input device for computers having ball with rotational sensors

A pen-type input device for a computer, comprising:

• (a) a pen-like elongated handle;
• (b) a ball rotatably supported by said handle with a portion of said ball projecting outwardly from an end of said handle;
• (c) first and second rotating detection members mounted in said handle and rotatable, upon frictional engagement with said ball, about first and second axes, respectively, said first and second axes being perpendicular to one another, each of said first and second rotating detection members being composed of a core shaft frictionally engageable with said ball for rotating a corresponding one of said first and second rotating detection members, and a pattern pipe firmly fitted over said core shaft;
• (d) at least one pattern composed of a series of alternating light-reflecting portions and light-absorbing portions disposed circumferentially along an outer peripheral surface of said pattern pipe of each of said first and second rotating detection members for detecting a direction of rotation of said ball and an amount of movement of said ball;
• (e) first and second circuit boards mounted in said handle and each having a detecting circuit;
• (f) first and second photodetectors each composed of a light-emitting device and a light-sensitive device and packaged on said first and second circuit boards, respectively, in corresponding relation to said first and second rotating detection members, respectively;
• and
• (g) means associated with each of said first and second photodetectors and defining at least one pair of first and second light paths extending such that light emitted from each respective light-emitting device is guided through said first light path onto said pattern and light reflected back from said pattern is guided through said second light path onto each respective light-sensitive device.